Method and apparatus for the crust-freezing/cooling/deep-freezing treatment of products

ABSTRACT

Methods and apparatus for freezing a product. The product is frozen in a treatment container which contains a vibrating support. The vibrating support is capable of receiving a film of a cryogenic liquid. A heated temperature probe, located just before the outlet of the treatment container, measures the temperature at that location. The supply system for the cryogenic liquid has a proportional valve. A data acquisition and processing unit receives the temperature information and controls the opening of the proportional valve.

BACKGROUND

The present invention relates to the field of methods and installationsfor the cryogenic treatment of products, particularly food products, thetreatment in question being in particular crust-freezing (deep-freezingsome or all of the surface of the product), cooling or deep-freezingtreatments.

Food products are conventionally frozen in freezing tunnels where thecooling is obtained by mechanical means.

These food products to be frozen are often tacky and adhere to theconveyor belts of the freezing tunnel on which they are carried, thusposing a problem of maintenance and hygiene.

Furthermore, these products may not be very compact and may readilydeform, thereby losing their intended shape when they are handled. Forexample, this is the case with vegetable croquettes which are extremelydifficult to handle.

In document EP-A-505 222, the Applicant proposed a novel concept for amethod of freezing food products, according to which the product isbrought in contact with a refrigerating surface which results from theuse of a vibrating support and a liquefied gas, the refrigeratingsurface consisting of a liquefied gas film arranged on the support.

According to this prior art, the products do not adhere at all to thesupport even if they are very tacky, despite the thickness of the filmpossibly being very small, and it seems very likely that the productthus treated floats on the surface of the liquefied gas film by acalefaction effect, and regularly turns over in this film so as to avoidany risk of adhesion to the support.

Typically, this system operates in the following way: a large quantityof liquid nitrogen is injected into the container, which is for exampleconfigured with a slightly upward slope. The liquid overspill leaves theapparatus with the products. The nitrogen is then separated from theproducts by a grille located at the exit of the device. The nitrogenrecovered in this way is recycled: it is collected in a reservoir thenpumped by a piston pump and returns to the treatment container.

The level of nitrogen is kept substantially constant in the reservoirowing to a valve driven by a probe, which measures the liquid nitrogenlevel therein.

The nitrogen thus flows in a semi-closed circuit, and leaves the circuitonly by evaporation in contact with the products; this loss of nitrogenis compensated for continuously by the supply of the reservoir. Theproducts pass through the container only once.

It should be emphasized that this prior art system has a number ofadvantages, including:

-   -   the level of liquid nitrogen is stable;    -   the treatment of the products is uniform;    -   the intensity of the treatment can be adjusted by modifying the        slope of the container;    -   the treatment time can be adjusted by modifying the amplitude of        the vibrations;    -   the principle is simple, easy to use and easy to regulate;    -   the substantial injection of nitrogen into the container        (injection rate=pumping rate) makes it possible to obtain very        efficient treatment of the products.

Nevertheless, the Applicant has now realized that this system should beimproved, particularly regarding the following aspects:

-   -   certain drawbacks have been found, associated with the presence        of the pump which represents the critical element of the system:        this pump consumes a non-negligible quantity of compressed air        and, when the throughput of the products to be treated is very        large, limits the overall cooling capacity of the system by its        pumping capacity,    -   furthermore, the system poses problems for small and powdered        products: this is because the size of the product may become        less than the size of the holes in the grille, so that it flows        in a closed circuit with the nitrogen, which is clearly        unsatisfactory in terms of sanitation.

It can therefore be seen that the drawbacks listed above are essentiallyconnected with the presence of the pump.

SUMMARY

In this context, it is an object of the present invention to provideoperating conditions which make it possible to remove this pump, toreplace it with a device which can ensure a constant temperature of theproducts after treatment, and to keep a constant level of nitrogen inthe treatment container without requiring nitrogen recycling.

To this end, the invention relates to a method for the total or partialfreezing of a product, in particular a food product, according to which,in order to freeze the product on at least one of its surfaces, theproduct is brought in contact in a treatment container with arefrigerating surface which results from the use of a vibrating supportand a film of a cryogenic liquid placed on said support, characterizedby the use of the following steps:

-   -   providing a heated temperature probe, which is located in the        treatment container just before the exit of the products from        the container and which can measure the temperature at the place        where it is located,    -   providing means for supplying the container with cryogenic        liquid, which have a proportional valve;    -   providing a data acquisition and processing unit which can        receive the temperature information provided by said probe and        can retroact if necessary on the opening factor of said        proportional valve.

The invention includes both methods and apparatus to achieve the desiredresults, as described, but is not limited to the various embodimentsdisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature and objects for the presentinvention, reference should be made to the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like elements are given the same or analogous reference numbersand wherein:

FIG. 1 illustrates a schematic view of one embodiment of a freezingapparatus with a vibrating support;

FIG. 2 illustrates a schematic view, according to one embodiment of thecurrent invention, of a freezing apparatus with a vibrating support indownward sloping orientation;

FIG. 3 illustrates a schematic view, according to one embodiment of thecurrent invention, of a freezing apparatus with a vibrating support inan upwardly sloping orientation;

FIG. 4 illustrates a schematic view, according to a second embodiment ofthe current invention, of a freezing apparatus with a vibrating supportin a downward sloping orientation; and

FIG. 5 illustrates a schematic view, according to a second embodiment ofthe current invention, of a freezing apparatus with a vibrating supportin an upwardly sloping orientation.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to methods and apparatus for the total orpartial freezing of a product, in particular a food product, bycontacting at least one surface of the product with a cryogenic liquidlocated on a vibrating support.

The method according to the invention may furthermore employ one or moreof the following characteristics:

-   -   the vibrating support has a slightly downward slope ending in a        slight rise which can thus contain a certain quantity of        cryogenic liquid, and said temperature probe is located        substantially at the position where the cryogenic liquid        accumulates,    -   the vibrating support has an upward slope. A grille, which can        filter some or all of the cryogenic liquid entrained with the        products as they progress upward, is in this case advantageously        arranged on some or all of the surface of the vibrating support,    -   the following temperature regulation is furthermore used:

i) a product temperature probe, which can measure the temperature of theproducts after treatment, is provided in the passage of the products atthe exit of the treatment container;

j) a data acquisition and processing unit is provided, which can receivethe temperature information provided by said product temperature probeand can retroact if necessary on means for varying the inclination slopeof the support and/or on means for varying the vibration frequency ofthe support and/or on the opening factor of said proportional valve,

-   -   the following safety regulation is furthermore used:

a) a safety temperature probe is provided in the treatment container,slightly in front of the exit of the products from the container, andcan measure the temperature at the place where it is located,

b) said means for supplying the container with cryogenic liquid have anon/off valve (safety valve);

c) a data acquisition and processing unit is provided, which can receivethe temperature information provided by said safety temperature probeand can retroact if necessary in order to open or close said on/off(safety) valve,

-   -   the cryogenic liquid is liquid nitrogen.

The present invention also relates to an installation for the total orpartial freezing of a product, in particular a food product, comprisinga treatment container which comprises a vibrating support capable ofreceiving a film of a cryogenic liquid, characterized in that itcomprises:

-   -   a heated temperature probe, which is located in the treatment        container just before the exit of the products from the        container and which can measure the temperature at the place        where it is located,    -   means for supplying the container with cryogenic liquid, which        have a proportional valve;    -   a data acquisition and processing unit which can receive the        temperature information provided by said probe and can retroact        if necessary on the opening factor of said proportional valve.

The installation according to the invention may furthermore employ oneor more of the following characteristics:

-   -   the vibrating support has a slightly downward slope ending in a        slight rise which can thus contain a certain quantity of        cryogenic liquid, and said temperature probe is located        substantially at the position where the cryogenic liquid        accumulates,    -   the vibrating support has an upward slope. A grille, which can        filter some or all of the cryogenic liquid entrained with the        products as they progress upward, is in this case advantageously        arranged on some or all of the surface of the vibrating support,    -   the installation furthermore comprises:

i) a product temperature probe which is located in the passage of theproducts at the exit of the treatment container and which can measurethe temperature of the products after treatment;

j) a data acquisition and processing unit, which can receive thetemperature information provided by said product temperature probe andcan retroact if necessary on means for varying the inclination slope ofthe support and/or on means for varying the vibration frequency of thesupport and/or on the opening factor of said proportional valve,

-   -   said means for supplying the container with cryogenic liquid        have an on/off safety valve, and the installation furthermore        comprises:

a) a safety temperature probe which is located in the treatmentcontainer, slightly in front of the exit of the products from thecontainer, and which can measure the temperature at the place where itis located,

b) a data acquisition and processing unit, which can receive thetemperature information provided by said safety temperature probe andcan retroact if necessary in order to open or close said on/off valve.

FIG. 1 represents a schematic view of a freezing installation with avibrating support according to the prior art, as illustrated by thedocument EP-A-505222 mentioned previously in the present description.

This schematic view shows the container 1 (the vibration means of whichhave not been represented here for the sake of clarity) supplied withproducts 2 to be frozen, and with liquid nitrogen via the intake means4.

For this embodiment, the container is in an upward slope situation.

The overspill of cryogenic liquid leaves the apparatus with theproducts. The nitrogen is then separated from the products by a grillesystem 5.

As can be seen in the figure, the nitrogen recovered in this way isrecycled (loop 3) in the following manner: the nitrogen is collected ina reservoir (4) then pumped by a piston pump, and thus returns to thetreatment container (return pipe 6).

The level of nitrogen is kept substantially constant in the reservoirowing to a valve 7 driven by a probe 8, which measures the liquidnitrogen level.

In summary:

-   -   the nitrogen flows in a semi-closed circuit: it leaves the        circuit only by evaporation in contact with the products. This        loss of nitrogen is compensated for continuously by the supply        of the reservoir with fresh cryogenic liquid (9),    -   the products pass through the container only once.

FIG. 2 in turn illustrates an embodiment of the invention which will nowbe described in detail.

Here, the treatment container 1 is set with a slightly downward slopeand ends in a slight rise in order to contain a small quantity ofcryogenic liquid.

A temperature probe 10 is placed in the treatment container, slightly infront of the product exit and substantially at the position where theliquid nitrogen accumulates and the level stabilizes.

The temperature read by this probe decreases when the level of nitrogenin the container rises, which has the effect of reducing (via theregulator 11) the opening of a proportional valve 12 (which may bereferred to as a “process” valve) and therefore the intake of freshliquid nitrogen (10). Since the nitrogen supply is reduced, the leveldescends again and stabilizes.

Similarly, the temperature read by the probe 10 will rise if a decreaseof the liquid nitrogen level is observed, which has the effect ofincreasing the opening factor of the valve 12. Since the injection ofnitrogen is enhanced, the nitrogen level will rise again and stabilize.

Thus, while the nitrogen bed in the prior art installations wascontrolled by the overspill using a closed-circuit recycling pump, herethe nitrogen bed is controlled dynamically by continuously adapting thequantity of nitrogen injected into the machine, whatever the consumptionof the apparatus.

According to the invention, the temperature probe is of the “heated”type. This is because the work conducted by the Applicant has shown thatit is not sensible to use a traditional probe in this situation. Infact, when the level of cryogenic liquid rises and touches the probe,the latter will typically see a temperature close to −200° C., forexample. When the liquid level descends again, the probe initiallyremains surrounded by a very cold gas phase (the temperature of which isclose to −200° C.) which means that the probe sees (and thereforereports) only very little difference between the situation when ittouches the cryogenic liquid film and the situation when it does nottouch it.

Hence the advantage of heating the probe continuously.

An exemplary embodiment of such a heated probe will be described below,specifically a probe of the “double Pt100” type marketed by a largenumber of suppliers in this field of temperature measurement.

The probe in question is composed of:

-   -   A temperature probe with a platinum resistor operating in the        following way, the resistance varies according to the        temperature: the resistance is for example 100 ohms at 0° C.,        and the resistance increases when the temperature increases.        Similarly, the resistance decreases when the temperature        decreases (for example: 138.51 ohms at 100° C. and 60.26 ohms at        −100° C.). An instrument connected to this resistor can measure        the resistance value and deduce the temperature therefrom by        using a conversion table.    -   A second temperature probe with a platinum resistor may be used        in the same way, thus making it possible to check the        temperature measured by the first probe.    -   Two connecting wires attached to the first platinum resistor and        two connecting wires attached to the second platinum resistor.    -   Stainless steel protection around this assembly: a stainless        steel tube plugged at its two ends and allowing the connecting        wires to pass through.    -   A thermal connection material between the platinum resistor        temperature probes and the stainless steel protection.

The traditional use of such a “double Pt100” probe is as follows:

The resistance value of the platinum resistors varies according to thetemperature. When the temperature increases, the resistance increases.Similarly, the resistance decreases when the temperature decreases (forexample: 138.51 ohms at 100° C. and 60.26 ohms at −100° C.).

The first platinum resistor is connected to an instrument which measuresthe value of the resistance and deduces the temperature therefrom byusing a conversion table. The second platinum resistor temperature probeis used in the same way, and thus makes it possible to check thetemperature measured by the first probe.

According to the present invention, this probe is utilized in anotherway by making it a “heated probe”, in the following manner.

The first platinum resistor is supplied continuously with a voltage of 5volts. It therefore dissipates a variable power according to itstemperature (0.25 watt at 0° C.) which causes slight heating that alsovaries according to the temperature (from +10 to +80° C. depending onthe ambient temperature).

The second platinum resistor is used traditionally by being connected toa resistance measuring device with calculation and display of thetemperature. The temperature thus measured is therefore influenced bythe other platinum resistor, which dissipates power.

The device is then ready to operate close to a level of cryogenicliquid, for example liquid nitrogen:

When the probe is positioned above the liquid nitrogen, without contactwith the liquid, the ambient temperature of the gases is very close to−196° C., but with the power dissipation of the first platinum resistor,the temperature of the probe assembly and therefore the measuredtemperature is about −130° C.

When the probe assembly comes in contact with the liquid nitrogen, thethermal transfer between the probe and the liquid is much greater thanwhen the probe was positioned in a gaseous medium. The temperature thendecreases rapidly and approaches −196° C.

This device therefore makes it very easy to determine whether the liquidnitrogen level lies above or below this double temperature probe: If themeasured temperature is less than −180° C., this implies that there iscontact between the probe and the liquid, but if the measuredtemperature is above −180° C., this implies that there is no contactbetween the probe and the liquid.

Experience shows that this device is simple, inexpensive, reliable,readily available and requires no maintenance. Furthermore, since itwithstands well the vibrations caused by the vibrating support duringoperation, it is entirely suitable for measuring and regulating thecryogenic liquid level in this type of machine.

For illustration, if the treatment container is supplied with a largethroughput of products to be treated, a large quantity of liquid will bevaporized and the valve 12 will then open sufficiently to compensate forthis demand while maintaining a constant temperature of the products atthe exit of the machine. If the machine is no longer supplied withproducts, conversely, the valve 12 will have its opening reduced so asto deliver only the quantity sufficient to maintain the level in thecontainer (keeping the machine cold).

The presence of a second injection control can also be seen in FIG. 2,the purpose of which is not to adjust the quantity of liquid nitrogeninjected but to cut the supply if the system (probe 13, regulator 14,on/off valve 15) drifts. If the regulation of the injection as describedabove drifts for an unknown reason, therefore, the liquid nitrogen willaccumulate at the low point of the apparatus, at the position where theslope of the container changes. The probe 13 will then detect anyabnormal rise of the nitrogen level by a drop in temperature. When thislevel reaches an allowed maximum (setpoint), it will cut the nitrogensupply to the system via the safety valve 15 before the liquid can reachthe edge of the container. Any risk of overflow will then be averted.

Here again, in view of its situation, the safety probe is preferably ofthe “heated” type.

The valve 15 then operates according to the following logic:

-   -   Level less than maximum tolerated level→valve open;    -   Level greater than or equal to the maximum tolerated level→valve        closed.

FIG. 2 has just illustrated a downward slope configuration. At theposition where the slope changes, a small “pool” is typically createdwith a depth of close to 0.5 cm (this is given only as an illustrationof the orders of magnitude) while upstream of the slope, facing the exitof the means 4, the depth is almost zero (nitrogen runoff).

FIG. 3 in turn illustrates a container in an upward slope position withthe same constituent elements, and therefore the same numericalreferences.

In fact, although the installation of FIG. 2 is more particularlysuitable for small products (such as potato powders, grated cheese,etc.), the nitrogen level of the treatment container with a downwardslope may prove insufficient for some larger products (such as poultrycubes).

Orienting the container with a slightly upward slope makes it possibleto create a nitrogen bed at the bottom of the container on the productentry side (typically a depth of close to 2 cm upstream of the slope,while the depth at the end of the upward slope is close to 0).

Owing to the “bath” effect thus created, the treatment is moreintensive.

It should be noted that in this upward slope situation, it is highlyadvantageous to provide a grille (not shown) over some or all of thesurface of the vibrating support 1, which can filter some or all of thecryogenic liquid entrained with the products as they progress upward.The cryogenic liquid “filtered” in this way then descends again towardthe upstream side of the upward slope.

In the case of either FIG. 2 or FIG. 3, the losses of cryogenic liquidare very small.

In summary, the embodiments of the invention as illustrated in FIGS. 2and 3 make it possible to omit the pump of the prior art while keepingconstant the amount of cooling (negative calories) received by theproduct.

The embodiments explained here will be referred to below as “levelregulation”.

FIGS. 4 and 5 illustrate an advantageous embodiment of the invention(respectively in downward and upward slope situations) in which a probefor measuring the exit temperature of the products is furthermore used.

In fact, it has been found that for some user sites where the initialtemperature of the incoming products can vary substantially from onetime of day to another, the level regulation illustrated above in FIGS.2 and 3 may be found to perform unsatisfactorily. According to thepresent invention, it is then more particularly advantageous to applyregulation to the exit temperature of the products in addition, asdescribed below. As will be seen, this regulation will furthermore makeit possible to adapt the temperature drop applied to the products.

In this situation, the “product” temperature probe is situated in a lessrigorous environment than the temperature probe present at the exit ofthe container, and this “product” temperature probe may therefore be ofthe traditional (unheated) type.

FIG. 4 shows the container 1, supplied with products 2 to be frozen andwith liquid nitrogen via the intake means 4. Here, the treatmentcontainer 1 is set with a slightly downward slope and ends in a slightrise in order to contain a small quantity of cryogenic liquid.

According to the invention, a heated temperature probe 10 is placed inthe treatment container, slightly in front of the product exit andsubstantially at the position where the liquid nitrogen accumulates andthe level stabilizes, and as described above makes it possible toregulate the quantity of fresh cryogenic liquid re-injected into thesystem via the valve 12 and the regulator 11.

This embodiment, however, also monitors the final temperature of theproducts after treatment via the probe 20 and, according to the resultof this monitoring, retroacts as appropriate on the slope of thecontainer 1 and/or on the vibration frequency (via the unit 21 and themeans 22 for varying the slope of the container and/or the vibrationfrequency).

As a variant (not shown), it is also possible to retroact on the openingfactor of the valve 12.

The system thus adapts its operation so as to obtain a constanttemperature of the products, irrespective of the initial conditions ofinput rate and initial temperature.

This embodiment will be referred to below as “temperature regulation”.

For illustration:

-   -   in the case of retroaction on the vibration frequency: if the        products reentering the system are too hot for an unknown or        miscellaneous reason, then the level regulation described above        which applies a constant temperature drop may prove insufficient        and lead to products which also emerge too hot.

The system will then retroact on the vibration frequency in order tomodify the transit time of the products through the container, in theexample mentioned here by reducing the vibration frequency, which willmake it possible to agitate the products less rapidly along their pathand therefore leave them in the liquid nitrogen for longer (and thusreach the desired lower temperature by successive iterations).

-   -   in the case of retroaction on the slope of the container: here,        the adjustment will affect the depth of liquid nitrogen to which        the product is exposed.

Still in the example where the products reenter the system too hot, thesystem will in this case reduce the downward slope or even, in certaincases, create an upward slope so as firstly to slow the rate of progressof the products through the container and secondly to create a cryogenicliquid bed, and increase its depth according to requirements.

The treatment time will be longer, and the contact of the product withthe liquid will then be more complete and more intense, which will makeit possible to lower the final temperature of the products to thedesired level by successive iterations.

It should be noted that although the safety control described above inthe context of FIGS. 2 and 3 (13/14/15) has not been described here inthe context of FIGS. 4 and 5, it may readily and even veryadvantageously be present as well to supplement the “level” and“temperature” regulations.

The advantages of the invention (“level regulation” optionallysupplemented by the “temperature regulation”) may then be described asfollows:

-   -   elimination of the pump and the cross-contaminations due to the        recirculation of nitrogen;    -   the temperature of the products after treatment is stable,        whatever the rate of incoming products and their temperature        before treatment;    -   the treatment time can be adjusted by modifying the slope of the        apparatus;    -   powders can be treated (this has been done successfully for        potato powders or chocolate powders);    -   the equipment is very simple to clean because it involves very        few mechanisms;    -   the reliability of the system is very greatly improved. In        particular, the risks of breakdown associated with the pump are        eliminated;    -   there is no recycling circuit, and the nitrogen losses are        therefore minimized.

For medium-sized products it will be advantageous to use the embodimentof FIG. 5, which is identical to that of FIG. 4 in all regards apartfrom the fact that the container is in an upward slope situation.

Although the invention has been more particularly illustrated above withreference to liquid nitrogen, other cryogenic liquids may be envisagedwithout departing from the scope of the invention in any way.

Likewise, besides the food products to which the invention moreparticularly relates, it is also possible to treat industrial productssuch as fatty materials or waxes whose melting points are close toambient temperature.

It will be understood that many additional changes in the details,materials, steps and arrangement of parts, which have been hereindescribed in order to explain the nature of the invention, may be madeby those skilled in the art within the principle and scope of theinvention as expressed in the appended claims. Thus, the presentinvention is not intended to be limited to the specific embodiments inthe examples given above.

1. A method which may be used for freezing a food product, said methodcomprising: a) freezing at least one surface of the food product,wherein said freezing: 1) comprises bringing said food product intocontact with a refrigerating surface; 2) takes place in a treatmentcontainer; and 3) results from the use of a vibrating support and a filmof a cryogenic liquid placed on said vibrating support, wherein saidvibrating support has an upward slope; b) providing a first heatedtemperature probe at a location immediately prior to an exit of saidfood product from said treatment container, wherein said first heatedtemperature probe measures a temperature at its location: c) providing acryogenic liquid supply system, wherein said cryogenic liquid supplysystem comprises a proportional valve; d) providing a first dataacquisition and processing unit which receives temperature informationfrom said first heated temperature probe, and which can control anopening of said proportional valve; and e) providing a grill, wherein:a) said grill is substantially located on said refrigerating surface ofsaid vibrating support; and b) said grill removes at least part of saidcryogenic liquid from said food products as said food products pass oversaid grill.
 2. A method which may be used for freezing a food product,said method comprising: a) freezing at least one surface of the foodproduct, wherein said freezing: 1) comprises bringing said food productinto contact with a refrigerating surface; 2) takes place in a treatmentcontainer; and 3) results from the use of a vibrating support and a filmof a cryogenic liquid placed on said vibrating support; b) providing afirst heated temperature probe at a location immediately prior to anexit of said food product from said treatment container, wherein saidfirst heated temperature probe measures a temperature at its location:c) providing a cryogenic liquid supply system, wherein said cryogenicliquid supply system comprises a proportional valve; d) providing afirst data acquisition and processing unit which receives temperatureinformation from said first heated temperature probe, which can controlan opening of said proportional valve; e) providing a producttemperature probe, wherein said product temperature probe: 1) is locatedin the passage of said food products at an exit of said treatmentcontainer; and 2) measures a product temperature after freezing; and f)providing a second data acquisition and processing unit, wherein saidsecond data acquisition and processing unit: 1) receives temperatureinformation from said product temperature probe; and 2) controls atleast one member selected from the group consisting of: i) aninclination slope of said vibrating support; ii) a frequency ofvibration of said vibrating support; and iii) the opening of saidproportional valve.
 3. A method which may be used for freezing a foodproduct, said method comprising: a) freezing at least one surface of thefood product, wherein said freezing: 1) comprises bringing said foodproduct into contact with a refrigerating surface; 2) takes place in atreatment container; and 3) results from the use of a vibrating supportand a film of a cryogenic liquid placed on said vibrating support; b)providing a first heated temperature probe at a location immediatelyprior to an exit of said food product from said treatment container,wherein said first heated temperature probe measures a temperature atits location; c) providing a cryogenic liquid supply system, whereinsaid cryogenic liquid supply system comprises a proportional valve; d)providing a first data acquisition and processing unit which receivestemperature information from said first heated temperature probe, andwhich can control an opening of said proportional valve; e) providing asafety temperature probe in said treatment container, wherein saidsafety temperature probe: 1) is located slightly in front of said foodproduct's exit from said treatment container; and 2) measures atemperature at its location; f) providing an on/off valve for saidcryogenic liquid supply system; and g) providing a third dataacquisition and processing unit, wherein said third data acquisition andprocessing unit: 1) receives temperature information from said safetytemperature probe; and 2) can control said on/off valve in order to openor close said on/off valve.
 4. The method of claim 3, wherein saidsafety temperature probe is a heated probe.
 5. The method of claim 4,wherein: a) said safety temperature probe or said first heatedtemperature probe is a double probe comprising a first and a secondresistor; b) said first resistor is connected to an instrument whichmeasures resistance and deduces said temperature from a conversiontable; and c) said second resistor is supplied with a voltage whichgenerates heat.
 6. An apparatus which may be used to freeze a product,said apparatus comprising: a) a treatment container for at least oneproduct, wherein said treatment container comprises: 1) a vibratingsupport capable of receiving a film of a cryogenic liquid, wherein saidvibrating support has an upward slope; 2) an inlet; and 3) an outlet; b)a first heated temperature probe located before said outlet, whereinsaid first heated temperature probe measures a temperature at itslocation; c) a supply system for said cryogenic liquid, wherein saidsupply system comprises a proportional valve; d) a first dataacquisition and processing unit, wherein said first data acquisition andprocessing unit is capable of: 1) receiving temperature information fromsaid first heated temperature probe; and 2) controlling an opening ofsaid proportional valve; and e) a grill substantially located on asurface of said vibrating support, wherein said grill is capable offiltering at least part of said cryogenic liquid contained in saidproduct as said product passes over said grill.
 7. An apparatus whichmay be used to freeze a product, said apparatus comprising: a) atreatment container for at least one product, wherein said treatmentcontainer comprises: 1) a vibrating support capable of receiving a filmof a cryogenic liquid; 2) an inlet; and 3) an outlet; b) a first heatedtemperature probe located before said outlet, wherein said first heatedtemperature probe measures a temperature at its location; c) a supplysystem for said cryogenic liquid, wherein said supply system comprises aproportional valve; d) a first data acquisition and processing unit,wherein said first data acquisition and processing unit is capableof: 1) receiving temperature information from said first heatedtemperature probe; and 2) controlling an opening of said proportionalvalve; e) a product temperature probe located near said outlet, whereinsaid product temperature probe is capable of measuring a temperature ofsaid product as it leaves said treatment container; and f) a second dataacquisition and processing unit, wherein said second data acquisitionand processing unit: 1) receives temperature information from saidproduct temperature probe; and 2) controls at least one member selectedfrom the group consisting of: i) an inclination slope of said vibratingsupport; ii) a frequency of vibration of said vibrating support; andiii) the opening of said proportional valve.
 8. An apparatus which maybe used to freeze a product, said apparatus comprising: a) a treatmentcontainer for at least one product, wherein said treatment containercomprises: 1) a vibrating support capable of receiving a film of acryogenic liquid; 2) an inlet; and 3) an outlet; b) a first heatedtemperature probe located before said outlet, wherein said first heatedtemperature probe measures a temperature at its location; c) a supplysystem for said cryogenic liquid, wherein said supply system comprises aproportional valve; d) a first data acquisition and processing unit,wherein said first data acquisition and processing unit is capableof: 1) receiving temperature information from said first heatedtemperature probe; and 2) controlling an opening of said proportionalvalve; e) an on/off valve for said supply system; f) a safetytemperature probe located near said outlet, wherein said safetytemperature probe is capable of measuring a temperature at its location;and g) a third data acquisition and processing unit, wherein said thirddata acquisition and processing unit: 1) is capable of receivingtemperature information from said safety temperature probe; and 2) iscapable of controlling the opening or closing of said on/off valve. 9.The apparatus of claim 8, wherein said safety temperature probe is aheated probe.
 10. The apparatus of claim 9, wherein: a) said safetytemperature probe or said first heated temperature probe is a doubleprobe comprising a first and a second resistor; b) said first resistoris connected to an instrument which measures resistance and deduces saidtemperature from a conversion table; and c) said second resistor issupplied with a voltage which generates heat.
 11. An apparatus which maybe used to freeze a product, said apparatus comprising: a) a treatmentcontainer for at least one product, wherein said treatment containercomprises: 1) a vibrating support capable of receiving a film of acryogenic liquid; 2) an inlet; and 3) an outlet; b) a first heatedtemperature probe located before said outlet, wherein said first heatedtemperature probe measures a temperature at its location; c) a supplysystem for said cryogenic liquid, wherein said supply system comprises aproportional valve; d) a first data acquisition and processing unit,wherein said first data acquisition and processing unit is capableof: 1) receiving temperature information from said first heatedtemperature probe; and 2) influencing an opening of said proportionalvalve; e) a product temperature probe located near said outlet, whereinsaid product temperature probe is capable of measuring a temperature ofsaid product as it leaves said treatment container; f) a second dataacquisition and processing unit, wherein said second data acquisitionand processing unit: 1) receives temperature information from saidproduct temperature probe; and 2) controls at least one member selectedfrom the group consisting of: i) an inclination slope of said support;ii) a frequency of vibration of said support; and iii) the opening ofsaid proportional valve; g) an on/off valve for said supply system; h) asafety temperature probe located near said outlet, wherein said safetytemperature probe is a heated probe capable of measuring a temperatureat its location; and i) a third data acquisition and processing unit,wherein said third data acquisition and processing unit: 1) is capableof receiving temperature information from said safety temperature probe;and 2) is capable of influencing an opening or closing of said on/offvalve.
 12. The apparatus of claim 11, wherein: a) said safetytemperature probe or said first heated temperature probe is a doubleprobe comprising a first and a second resistor; b) said first resistoris connected to an instrument which measures resistance and deduces saidtemperature from a conversion table; and c) said second resistor issupplied with a voltage which generates heat.